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1 | /* audit.c -- Auditing support | |
2 | * Gateway between the kernel (e.g., selinux) and the user-space audit daemon. | |
3 | * System-call specific features have moved to auditsc.c | |
4 | * | |
5 | * Copyright 2003-2007 Red Hat Inc., Durham, North Carolina. | |
6 | * All Rights Reserved. | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License as published by | |
10 | * the Free Software Foundation; either version 2 of the License, or | |
11 | * (at your option) any later version. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License | |
19 | * along with this program; if not, write to the Free Software | |
20 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
21 | * | |
22 | * Written by Rickard E. (Rik) Faith <faith@redhat.com> | |
23 | * | |
24 | * Goals: 1) Integrate fully with Security Modules. | |
25 | * 2) Minimal run-time overhead: | |
26 | * a) Minimal when syscall auditing is disabled (audit_enable=0). | |
27 | * b) Small when syscall auditing is enabled and no audit record | |
28 | * is generated (defer as much work as possible to record | |
29 | * generation time): | |
30 | * i) context is allocated, | |
31 | * ii) names from getname are stored without a copy, and | |
32 | * iii) inode information stored from path_lookup. | |
33 | * 3) Ability to disable syscall auditing at boot time (audit=0). | |
34 | * 4) Usable by other parts of the kernel (if audit_log* is called, | |
35 | * then a syscall record will be generated automatically for the | |
36 | * current syscall). | |
37 | * 5) Netlink interface to user-space. | |
38 | * 6) Support low-overhead kernel-based filtering to minimize the | |
39 | * information that must be passed to user-space. | |
40 | * | |
41 | * Example user-space utilities: http://people.redhat.com/sgrubb/audit/ | |
42 | */ | |
43 | ||
44 | #include <linux/init.h> | |
45 | #include <asm/types.h> | |
46 | #include <asm/atomic.h> | |
47 | #include <linux/mm.h> | |
48 | #include <linux/module.h> | |
49 | #include <linux/slab.h> | |
50 | #include <linux/err.h> | |
51 | #include <linux/kthread.h> | |
52 | ||
53 | #include <linux/audit.h> | |
54 | ||
55 | #include <net/sock.h> | |
56 | #include <net/netlink.h> | |
57 | #include <linux/skbuff.h> | |
58 | #include <linux/netlink.h> | |
59 | #include <linux/freezer.h> | |
60 | #include <linux/tty.h> | |
61 | ||
62 | #include "audit.h" | |
63 | ||
64 | /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED. | |
65 | * (Initialization happens after skb_init is called.) */ | |
66 | #define AUDIT_DISABLED -1 | |
67 | #define AUDIT_UNINITIALIZED 0 | |
68 | #define AUDIT_INITIALIZED 1 | |
69 | static int audit_initialized; | |
70 | ||
71 | #define AUDIT_OFF 0 | |
72 | #define AUDIT_ON 1 | |
73 | #define AUDIT_LOCKED 2 | |
74 | int audit_enabled; | |
75 | int audit_ever_enabled; | |
76 | ||
77 | /* Default state when kernel boots without any parameters. */ | |
78 | static int audit_default; | |
79 | ||
80 | /* If auditing cannot proceed, audit_failure selects what happens. */ | |
81 | static int audit_failure = AUDIT_FAIL_PRINTK; | |
82 | ||
83 | /* | |
84 | * If audit records are to be written to the netlink socket, audit_pid | |
85 | * contains the pid of the auditd process and audit_nlk_pid contains | |
86 | * the pid to use to send netlink messages to that process. | |
87 | */ | |
88 | int audit_pid; | |
89 | static int audit_nlk_pid; | |
90 | ||
91 | /* If audit_rate_limit is non-zero, limit the rate of sending audit records | |
92 | * to that number per second. This prevents DoS attacks, but results in | |
93 | * audit records being dropped. */ | |
94 | static int audit_rate_limit; | |
95 | ||
96 | /* Number of outstanding audit_buffers allowed. */ | |
97 | static int audit_backlog_limit = 64; | |
98 | static int audit_backlog_wait_time = 60 * HZ; | |
99 | static int audit_backlog_wait_overflow = 0; | |
100 | ||
101 | /* The identity of the user shutting down the audit system. */ | |
102 | uid_t audit_sig_uid = -1; | |
103 | pid_t audit_sig_pid = -1; | |
104 | u32 audit_sig_sid = 0; | |
105 | ||
106 | /* Records can be lost in several ways: | |
107 | 0) [suppressed in audit_alloc] | |
108 | 1) out of memory in audit_log_start [kmalloc of struct audit_buffer] | |
109 | 2) out of memory in audit_log_move [alloc_skb] | |
110 | 3) suppressed due to audit_rate_limit | |
111 | 4) suppressed due to audit_backlog_limit | |
112 | */ | |
113 | static atomic_t audit_lost = ATOMIC_INIT(0); | |
114 | ||
115 | /* The netlink socket. */ | |
116 | static struct sock *audit_sock; | |
117 | ||
118 | /* Hash for inode-based rules */ | |
119 | struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS]; | |
120 | ||
121 | /* The audit_freelist is a list of pre-allocated audit buffers (if more | |
122 | * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of | |
123 | * being placed on the freelist). */ | |
124 | static DEFINE_SPINLOCK(audit_freelist_lock); | |
125 | static int audit_freelist_count; | |
126 | static LIST_HEAD(audit_freelist); | |
127 | ||
128 | static struct sk_buff_head audit_skb_queue; | |
129 | /* queue of skbs to send to auditd when/if it comes back */ | |
130 | static struct sk_buff_head audit_skb_hold_queue; | |
131 | static struct task_struct *kauditd_task; | |
132 | static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait); | |
133 | static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait); | |
134 | ||
135 | /* Serialize requests from userspace. */ | |
136 | DEFINE_MUTEX(audit_cmd_mutex); | |
137 | ||
138 | /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting | |
139 | * audit records. Since printk uses a 1024 byte buffer, this buffer | |
140 | * should be at least that large. */ | |
141 | #define AUDIT_BUFSIZ 1024 | |
142 | ||
143 | /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the | |
144 | * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */ | |
145 | #define AUDIT_MAXFREE (2*NR_CPUS) | |
146 | ||
147 | /* The audit_buffer is used when formatting an audit record. The caller | |
148 | * locks briefly to get the record off the freelist or to allocate the | |
149 | * buffer, and locks briefly to send the buffer to the netlink layer or | |
150 | * to place it on a transmit queue. Multiple audit_buffers can be in | |
151 | * use simultaneously. */ | |
152 | struct audit_buffer { | |
153 | struct list_head list; | |
154 | struct sk_buff *skb; /* formatted skb ready to send */ | |
155 | struct audit_context *ctx; /* NULL or associated context */ | |
156 | gfp_t gfp_mask; | |
157 | }; | |
158 | ||
159 | struct audit_reply { | |
160 | int pid; | |
161 | struct sk_buff *skb; | |
162 | }; | |
163 | ||
164 | static void audit_set_pid(struct audit_buffer *ab, pid_t pid) | |
165 | { | |
166 | if (ab) { | |
167 | struct nlmsghdr *nlh = nlmsg_hdr(ab->skb); | |
168 | nlh->nlmsg_pid = pid; | |
169 | } | |
170 | } | |
171 | ||
172 | void audit_panic(const char *message) | |
173 | { | |
174 | switch (audit_failure) | |
175 | { | |
176 | case AUDIT_FAIL_SILENT: | |
177 | break; | |
178 | case AUDIT_FAIL_PRINTK: | |
179 | if (printk_ratelimit()) | |
180 | printk(KERN_ERR "audit: %s\n", message); | |
181 | break; | |
182 | case AUDIT_FAIL_PANIC: | |
183 | /* test audit_pid since printk is always losey, why bother? */ | |
184 | if (audit_pid) | |
185 | panic("audit: %s\n", message); | |
186 | break; | |
187 | } | |
188 | } | |
189 | ||
190 | static inline int audit_rate_check(void) | |
191 | { | |
192 | static unsigned long last_check = 0; | |
193 | static int messages = 0; | |
194 | static DEFINE_SPINLOCK(lock); | |
195 | unsigned long flags; | |
196 | unsigned long now; | |
197 | unsigned long elapsed; | |
198 | int retval = 0; | |
199 | ||
200 | if (!audit_rate_limit) return 1; | |
201 | ||
202 | spin_lock_irqsave(&lock, flags); | |
203 | if (++messages < audit_rate_limit) { | |
204 | retval = 1; | |
205 | } else { | |
206 | now = jiffies; | |
207 | elapsed = now - last_check; | |
208 | if (elapsed > HZ) { | |
209 | last_check = now; | |
210 | messages = 0; | |
211 | retval = 1; | |
212 | } | |
213 | } | |
214 | spin_unlock_irqrestore(&lock, flags); | |
215 | ||
216 | return retval; | |
217 | } | |
218 | ||
219 | /** | |
220 | * audit_log_lost - conditionally log lost audit message event | |
221 | * @message: the message stating reason for lost audit message | |
222 | * | |
223 | * Emit at least 1 message per second, even if audit_rate_check is | |
224 | * throttling. | |
225 | * Always increment the lost messages counter. | |
226 | */ | |
227 | void audit_log_lost(const char *message) | |
228 | { | |
229 | static unsigned long last_msg = 0; | |
230 | static DEFINE_SPINLOCK(lock); | |
231 | unsigned long flags; | |
232 | unsigned long now; | |
233 | int print; | |
234 | ||
235 | atomic_inc(&audit_lost); | |
236 | ||
237 | print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit); | |
238 | ||
239 | if (!print) { | |
240 | spin_lock_irqsave(&lock, flags); | |
241 | now = jiffies; | |
242 | if (now - last_msg > HZ) { | |
243 | print = 1; | |
244 | last_msg = now; | |
245 | } | |
246 | spin_unlock_irqrestore(&lock, flags); | |
247 | } | |
248 | ||
249 | if (print) { | |
250 | if (printk_ratelimit()) | |
251 | printk(KERN_WARNING | |
252 | "audit: audit_lost=%d audit_rate_limit=%d " | |
253 | "audit_backlog_limit=%d\n", | |
254 | atomic_read(&audit_lost), | |
255 | audit_rate_limit, | |
256 | audit_backlog_limit); | |
257 | audit_panic(message); | |
258 | } | |
259 | } | |
260 | ||
261 | static int audit_log_config_change(char *function_name, int new, int old, | |
262 | uid_t loginuid, u32 sessionid, u32 sid, | |
263 | int allow_changes) | |
264 | { | |
265 | struct audit_buffer *ab; | |
266 | int rc = 0; | |
267 | ||
268 | ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE); | |
269 | audit_log_format(ab, "%s=%d old=%d auid=%u ses=%u", function_name, new, | |
270 | old, loginuid, sessionid); | |
271 | if (sid) { | |
272 | char *ctx = NULL; | |
273 | u32 len; | |
274 | ||
275 | rc = security_secid_to_secctx(sid, &ctx, &len); | |
276 | if (rc) { | |
277 | audit_log_format(ab, " sid=%u", sid); | |
278 | allow_changes = 0; /* Something weird, deny request */ | |
279 | } else { | |
280 | audit_log_format(ab, " subj=%s", ctx); | |
281 | security_release_secctx(ctx, len); | |
282 | } | |
283 | } | |
284 | audit_log_format(ab, " res=%d", allow_changes); | |
285 | audit_log_end(ab); | |
286 | return rc; | |
287 | } | |
288 | ||
289 | static int audit_do_config_change(char *function_name, int *to_change, | |
290 | int new, uid_t loginuid, u32 sessionid, | |
291 | u32 sid) | |
292 | { | |
293 | int allow_changes, rc = 0, old = *to_change; | |
294 | ||
295 | /* check if we are locked */ | |
296 | if (audit_enabled == AUDIT_LOCKED) | |
297 | allow_changes = 0; | |
298 | else | |
299 | allow_changes = 1; | |
300 | ||
301 | if (audit_enabled != AUDIT_OFF) { | |
302 | rc = audit_log_config_change(function_name, new, old, loginuid, | |
303 | sessionid, sid, allow_changes); | |
304 | if (rc) | |
305 | allow_changes = 0; | |
306 | } | |
307 | ||
308 | /* If we are allowed, make the change */ | |
309 | if (allow_changes == 1) | |
310 | *to_change = new; | |
311 | /* Not allowed, update reason */ | |
312 | else if (rc == 0) | |
313 | rc = -EPERM; | |
314 | return rc; | |
315 | } | |
316 | ||
317 | static int audit_set_rate_limit(int limit, uid_t loginuid, u32 sessionid, | |
318 | u32 sid) | |
319 | { | |
320 | return audit_do_config_change("audit_rate_limit", &audit_rate_limit, | |
321 | limit, loginuid, sessionid, sid); | |
322 | } | |
323 | ||
324 | static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sessionid, | |
325 | u32 sid) | |
326 | { | |
327 | return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, | |
328 | limit, loginuid, sessionid, sid); | |
329 | } | |
330 | ||
331 | static int audit_set_enabled(int state, uid_t loginuid, u32 sessionid, u32 sid) | |
332 | { | |
333 | int rc; | |
334 | if (state < AUDIT_OFF || state > AUDIT_LOCKED) | |
335 | return -EINVAL; | |
336 | ||
337 | rc = audit_do_config_change("audit_enabled", &audit_enabled, state, | |
338 | loginuid, sessionid, sid); | |
339 | ||
340 | if (!rc) | |
341 | audit_ever_enabled |= !!state; | |
342 | ||
343 | return rc; | |
344 | } | |
345 | ||
346 | static int audit_set_failure(int state, uid_t loginuid, u32 sessionid, u32 sid) | |
347 | { | |
348 | if (state != AUDIT_FAIL_SILENT | |
349 | && state != AUDIT_FAIL_PRINTK | |
350 | && state != AUDIT_FAIL_PANIC) | |
351 | return -EINVAL; | |
352 | ||
353 | return audit_do_config_change("audit_failure", &audit_failure, state, | |
354 | loginuid, sessionid, sid); | |
355 | } | |
356 | ||
357 | /* | |
358 | * Queue skbs to be sent to auditd when/if it comes back. These skbs should | |
359 | * already have been sent via prink/syslog and so if these messages are dropped | |
360 | * it is not a huge concern since we already passed the audit_log_lost() | |
361 | * notification and stuff. This is just nice to get audit messages during | |
362 | * boot before auditd is running or messages generated while auditd is stopped. | |
363 | * This only holds messages is audit_default is set, aka booting with audit=1 | |
364 | * or building your kernel that way. | |
365 | */ | |
366 | static void audit_hold_skb(struct sk_buff *skb) | |
367 | { | |
368 | if (audit_default && | |
369 | skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit) | |
370 | skb_queue_tail(&audit_skb_hold_queue, skb); | |
371 | else | |
372 | kfree_skb(skb); | |
373 | } | |
374 | ||
375 | /* | |
376 | * For one reason or another this nlh isn't getting delivered to the userspace | |
377 | * audit daemon, just send it to printk. | |
378 | */ | |
379 | static void audit_printk_skb(struct sk_buff *skb) | |
380 | { | |
381 | struct nlmsghdr *nlh = nlmsg_hdr(skb); | |
382 | char *data = NLMSG_DATA(nlh); | |
383 | ||
384 | if (nlh->nlmsg_type != AUDIT_EOE) { | |
385 | if (printk_ratelimit()) | |
386 | printk(KERN_NOTICE "type=%d %s\n", nlh->nlmsg_type, data); | |
387 | else | |
388 | audit_log_lost("printk limit exceeded\n"); | |
389 | } | |
390 | ||
391 | audit_hold_skb(skb); | |
392 | } | |
393 | ||
394 | static void kauditd_send_skb(struct sk_buff *skb) | |
395 | { | |
396 | int err; | |
397 | /* take a reference in case we can't send it and we want to hold it */ | |
398 | skb_get(skb); | |
399 | err = netlink_unicast(audit_sock, skb, audit_nlk_pid, 0); | |
400 | if (err < 0) { | |
401 | BUG_ON(err != -ECONNREFUSED); /* Shouldn't happen */ | |
402 | printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid); | |
403 | audit_log_lost("auditd dissapeared\n"); | |
404 | audit_pid = 0; | |
405 | /* we might get lucky and get this in the next auditd */ | |
406 | audit_hold_skb(skb); | |
407 | } else | |
408 | /* drop the extra reference if sent ok */ | |
409 | consume_skb(skb); | |
410 | } | |
411 | ||
412 | static int kauditd_thread(void *dummy) | |
413 | { | |
414 | struct sk_buff *skb; | |
415 | ||
416 | set_freezable(); | |
417 | while (!kthread_should_stop()) { | |
418 | /* | |
419 | * if auditd just started drain the queue of messages already | |
420 | * sent to syslog/printk. remember loss here is ok. we already | |
421 | * called audit_log_lost() if it didn't go out normally. so the | |
422 | * race between the skb_dequeue and the next check for audit_pid | |
423 | * doesn't matter. | |
424 | * | |
425 | * if you ever find kauditd to be too slow we can get a perf win | |
426 | * by doing our own locking and keeping better track if there | |
427 | * are messages in this queue. I don't see the need now, but | |
428 | * in 5 years when I want to play with this again I'll see this | |
429 | * note and still have no friggin idea what i'm thinking today. | |
430 | */ | |
431 | if (audit_default && audit_pid) { | |
432 | skb = skb_dequeue(&audit_skb_hold_queue); | |
433 | if (unlikely(skb)) { | |
434 | while (skb && audit_pid) { | |
435 | kauditd_send_skb(skb); | |
436 | skb = skb_dequeue(&audit_skb_hold_queue); | |
437 | } | |
438 | } | |
439 | } | |
440 | ||
441 | skb = skb_dequeue(&audit_skb_queue); | |
442 | wake_up(&audit_backlog_wait); | |
443 | if (skb) { | |
444 | if (audit_pid) | |
445 | kauditd_send_skb(skb); | |
446 | else | |
447 | audit_printk_skb(skb); | |
448 | } else { | |
449 | DECLARE_WAITQUEUE(wait, current); | |
450 | set_current_state(TASK_INTERRUPTIBLE); | |
451 | add_wait_queue(&kauditd_wait, &wait); | |
452 | ||
453 | if (!skb_queue_len(&audit_skb_queue)) { | |
454 | try_to_freeze(); | |
455 | schedule(); | |
456 | } | |
457 | ||
458 | __set_current_state(TASK_RUNNING); | |
459 | remove_wait_queue(&kauditd_wait, &wait); | |
460 | } | |
461 | } | |
462 | return 0; | |
463 | } | |
464 | ||
465 | static int audit_prepare_user_tty(pid_t pid, uid_t loginuid, u32 sessionid) | |
466 | { | |
467 | struct task_struct *tsk; | |
468 | int err; | |
469 | ||
470 | rcu_read_lock(); | |
471 | tsk = find_task_by_vpid(pid); | |
472 | if (!tsk) { | |
473 | rcu_read_unlock(); | |
474 | return -ESRCH; | |
475 | } | |
476 | get_task_struct(tsk); | |
477 | rcu_read_unlock(); | |
478 | err = tty_audit_push_task(tsk, loginuid, sessionid); | |
479 | put_task_struct(tsk); | |
480 | return err; | |
481 | } | |
482 | ||
483 | int audit_send_list(void *_dest) | |
484 | { | |
485 | struct audit_netlink_list *dest = _dest; | |
486 | int pid = dest->pid; | |
487 | struct sk_buff *skb; | |
488 | ||
489 | /* wait for parent to finish and send an ACK */ | |
490 | mutex_lock(&audit_cmd_mutex); | |
491 | mutex_unlock(&audit_cmd_mutex); | |
492 | ||
493 | while ((skb = __skb_dequeue(&dest->q)) != NULL) | |
494 | netlink_unicast(audit_sock, skb, pid, 0); | |
495 | ||
496 | kfree(dest); | |
497 | ||
498 | return 0; | |
499 | } | |
500 | ||
501 | struct sk_buff *audit_make_reply(int pid, int seq, int type, int done, | |
502 | int multi, const void *payload, int size) | |
503 | { | |
504 | struct sk_buff *skb; | |
505 | struct nlmsghdr *nlh; | |
506 | void *data; | |
507 | int flags = multi ? NLM_F_MULTI : 0; | |
508 | int t = done ? NLMSG_DONE : type; | |
509 | ||
510 | skb = nlmsg_new(size, GFP_KERNEL); | |
511 | if (!skb) | |
512 | return NULL; | |
513 | ||
514 | nlh = NLMSG_NEW(skb, pid, seq, t, size, flags); | |
515 | data = NLMSG_DATA(nlh); | |
516 | memcpy(data, payload, size); | |
517 | return skb; | |
518 | ||
519 | nlmsg_failure: /* Used by NLMSG_NEW */ | |
520 | if (skb) | |
521 | kfree_skb(skb); | |
522 | return NULL; | |
523 | } | |
524 | ||
525 | static int audit_send_reply_thread(void *arg) | |
526 | { | |
527 | struct audit_reply *reply = (struct audit_reply *)arg; | |
528 | ||
529 | mutex_lock(&audit_cmd_mutex); | |
530 | mutex_unlock(&audit_cmd_mutex); | |
531 | ||
532 | /* Ignore failure. It'll only happen if the sender goes away, | |
533 | because our timeout is set to infinite. */ | |
534 | netlink_unicast(audit_sock, reply->skb, reply->pid, 0); | |
535 | kfree(reply); | |
536 | return 0; | |
537 | } | |
538 | /** | |
539 | * audit_send_reply - send an audit reply message via netlink | |
540 | * @pid: process id to send reply to | |
541 | * @seq: sequence number | |
542 | * @type: audit message type | |
543 | * @done: done (last) flag | |
544 | * @multi: multi-part message flag | |
545 | * @payload: payload data | |
546 | * @size: payload size | |
547 | * | |
548 | * Allocates an skb, builds the netlink message, and sends it to the pid. | |
549 | * No failure notifications. | |
550 | */ | |
551 | static void audit_send_reply(int pid, int seq, int type, int done, int multi, | |
552 | const void *payload, int size) | |
553 | { | |
554 | struct sk_buff *skb; | |
555 | struct task_struct *tsk; | |
556 | struct audit_reply *reply = kmalloc(sizeof(struct audit_reply), | |
557 | GFP_KERNEL); | |
558 | ||
559 | if (!reply) | |
560 | return; | |
561 | ||
562 | skb = audit_make_reply(pid, seq, type, done, multi, payload, size); | |
563 | if (!skb) | |
564 | goto out; | |
565 | ||
566 | reply->pid = pid; | |
567 | reply->skb = skb; | |
568 | ||
569 | tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply"); | |
570 | if (!IS_ERR(tsk)) | |
571 | return; | |
572 | kfree_skb(skb); | |
573 | out: | |
574 | kfree(reply); | |
575 | } | |
576 | ||
577 | /* | |
578 | * Check for appropriate CAP_AUDIT_ capabilities on incoming audit | |
579 | * control messages. | |
580 | */ | |
581 | static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type) | |
582 | { | |
583 | int err = 0; | |
584 | ||
585 | switch (msg_type) { | |
586 | case AUDIT_GET: | |
587 | case AUDIT_LIST: | |
588 | case AUDIT_LIST_RULES: | |
589 | case AUDIT_SET: | |
590 | case AUDIT_ADD: | |
591 | case AUDIT_ADD_RULE: | |
592 | case AUDIT_DEL: | |
593 | case AUDIT_DEL_RULE: | |
594 | case AUDIT_SIGNAL_INFO: | |
595 | case AUDIT_TTY_GET: | |
596 | case AUDIT_TTY_SET: | |
597 | case AUDIT_TRIM: | |
598 | case AUDIT_MAKE_EQUIV: | |
599 | if (security_netlink_recv(skb, CAP_AUDIT_CONTROL)) | |
600 | err = -EPERM; | |
601 | break; | |
602 | case AUDIT_USER: | |
603 | case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG: | |
604 | case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2: | |
605 | if (security_netlink_recv(skb, CAP_AUDIT_WRITE)) | |
606 | err = -EPERM; | |
607 | break; | |
608 | default: /* bad msg */ | |
609 | err = -EINVAL; | |
610 | } | |
611 | ||
612 | return err; | |
613 | } | |
614 | ||
615 | static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type, | |
616 | u32 pid, u32 uid, uid_t auid, u32 ses, | |
617 | u32 sid) | |
618 | { | |
619 | int rc = 0; | |
620 | char *ctx = NULL; | |
621 | u32 len; | |
622 | ||
623 | if (!audit_enabled) { | |
624 | *ab = NULL; | |
625 | return rc; | |
626 | } | |
627 | ||
628 | *ab = audit_log_start(NULL, GFP_KERNEL, msg_type); | |
629 | audit_log_format(*ab, "user pid=%d uid=%u auid=%u ses=%u", | |
630 | pid, uid, auid, ses); | |
631 | if (sid) { | |
632 | rc = security_secid_to_secctx(sid, &ctx, &len); | |
633 | if (rc) | |
634 | audit_log_format(*ab, " ssid=%u", sid); | |
635 | else { | |
636 | audit_log_format(*ab, " subj=%s", ctx); | |
637 | security_release_secctx(ctx, len); | |
638 | } | |
639 | } | |
640 | ||
641 | return rc; | |
642 | } | |
643 | ||
644 | static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) | |
645 | { | |
646 | u32 uid, pid, seq, sid; | |
647 | void *data; | |
648 | struct audit_status *status_get, status_set; | |
649 | int err; | |
650 | struct audit_buffer *ab; | |
651 | u16 msg_type = nlh->nlmsg_type; | |
652 | uid_t loginuid; /* loginuid of sender */ | |
653 | u32 sessionid; | |
654 | struct audit_sig_info *sig_data; | |
655 | char *ctx = NULL; | |
656 | u32 len; | |
657 | ||
658 | err = audit_netlink_ok(skb, msg_type); | |
659 | if (err) | |
660 | return err; | |
661 | ||
662 | /* As soon as there's any sign of userspace auditd, | |
663 | * start kauditd to talk to it */ | |
664 | if (!kauditd_task) | |
665 | kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd"); | |
666 | if (IS_ERR(kauditd_task)) { | |
667 | err = PTR_ERR(kauditd_task); | |
668 | kauditd_task = NULL; | |
669 | return err; | |
670 | } | |
671 | ||
672 | pid = NETLINK_CREDS(skb)->pid; | |
673 | uid = NETLINK_CREDS(skb)->uid; | |
674 | loginuid = NETLINK_CB(skb).loginuid; | |
675 | sessionid = NETLINK_CB(skb).sessionid; | |
676 | sid = NETLINK_CB(skb).sid; | |
677 | seq = nlh->nlmsg_seq; | |
678 | data = NLMSG_DATA(nlh); | |
679 | ||
680 | switch (msg_type) { | |
681 | case AUDIT_GET: | |
682 | status_set.enabled = audit_enabled; | |
683 | status_set.failure = audit_failure; | |
684 | status_set.pid = audit_pid; | |
685 | status_set.rate_limit = audit_rate_limit; | |
686 | status_set.backlog_limit = audit_backlog_limit; | |
687 | status_set.lost = atomic_read(&audit_lost); | |
688 | status_set.backlog = skb_queue_len(&audit_skb_queue); | |
689 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0, | |
690 | &status_set, sizeof(status_set)); | |
691 | break; | |
692 | case AUDIT_SET: | |
693 | if (nlh->nlmsg_len < sizeof(struct audit_status)) | |
694 | return -EINVAL; | |
695 | status_get = (struct audit_status *)data; | |
696 | if (status_get->mask & AUDIT_STATUS_ENABLED) { | |
697 | err = audit_set_enabled(status_get->enabled, | |
698 | loginuid, sessionid, sid); | |
699 | if (err < 0) | |
700 | return err; | |
701 | } | |
702 | if (status_get->mask & AUDIT_STATUS_FAILURE) { | |
703 | err = audit_set_failure(status_get->failure, | |
704 | loginuid, sessionid, sid); | |
705 | if (err < 0) | |
706 | return err; | |
707 | } | |
708 | if (status_get->mask & AUDIT_STATUS_PID) { | |
709 | int new_pid = status_get->pid; | |
710 | ||
711 | if (audit_enabled != AUDIT_OFF) | |
712 | audit_log_config_change("audit_pid", new_pid, | |
713 | audit_pid, loginuid, | |
714 | sessionid, sid, 1); | |
715 | ||
716 | audit_pid = new_pid; | |
717 | audit_nlk_pid = NETLINK_CB(skb).pid; | |
718 | } | |
719 | if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) { | |
720 | err = audit_set_rate_limit(status_get->rate_limit, | |
721 | loginuid, sessionid, sid); | |
722 | if (err < 0) | |
723 | return err; | |
724 | } | |
725 | if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT) | |
726 | err = audit_set_backlog_limit(status_get->backlog_limit, | |
727 | loginuid, sessionid, sid); | |
728 | break; | |
729 | case AUDIT_USER: | |
730 | case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG: | |
731 | case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2: | |
732 | if (!audit_enabled && msg_type != AUDIT_USER_AVC) | |
733 | return 0; | |
734 | ||
735 | err = audit_filter_user(&NETLINK_CB(skb)); | |
736 | if (err == 1) { | |
737 | err = 0; | |
738 | if (msg_type == AUDIT_USER_TTY) { | |
739 | err = audit_prepare_user_tty(pid, loginuid, | |
740 | sessionid); | |
741 | if (err) | |
742 | break; | |
743 | } | |
744 | audit_log_common_recv_msg(&ab, msg_type, pid, uid, | |
745 | loginuid, sessionid, sid); | |
746 | ||
747 | if (msg_type != AUDIT_USER_TTY) | |
748 | audit_log_format(ab, " msg='%.1024s'", | |
749 | (char *)data); | |
750 | else { | |
751 | int size; | |
752 | ||
753 | audit_log_format(ab, " msg="); | |
754 | size = nlmsg_len(nlh); | |
755 | if (size > 0 && | |
756 | ((unsigned char *)data)[size - 1] == '\0') | |
757 | size--; | |
758 | audit_log_n_untrustedstring(ab, data, size); | |
759 | } | |
760 | audit_set_pid(ab, pid); | |
761 | audit_log_end(ab); | |
762 | } | |
763 | break; | |
764 | case AUDIT_ADD: | |
765 | case AUDIT_DEL: | |
766 | if (nlmsg_len(nlh) < sizeof(struct audit_rule)) | |
767 | return -EINVAL; | |
768 | if (audit_enabled == AUDIT_LOCKED) { | |
769 | audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid, | |
770 | uid, loginuid, sessionid, sid); | |
771 | ||
772 | audit_log_format(ab, " audit_enabled=%d res=0", | |
773 | audit_enabled); | |
774 | audit_log_end(ab); | |
775 | return -EPERM; | |
776 | } | |
777 | /* fallthrough */ | |
778 | case AUDIT_LIST: | |
779 | err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid, | |
780 | uid, seq, data, nlmsg_len(nlh), | |
781 | loginuid, sessionid, sid); | |
782 | break; | |
783 | case AUDIT_ADD_RULE: | |
784 | case AUDIT_DEL_RULE: | |
785 | if (nlmsg_len(nlh) < sizeof(struct audit_rule_data)) | |
786 | return -EINVAL; | |
787 | if (audit_enabled == AUDIT_LOCKED) { | |
788 | audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid, | |
789 | uid, loginuid, sessionid, sid); | |
790 | ||
791 | audit_log_format(ab, " audit_enabled=%d res=0", | |
792 | audit_enabled); | |
793 | audit_log_end(ab); | |
794 | return -EPERM; | |
795 | } | |
796 | /* fallthrough */ | |
797 | case AUDIT_LIST_RULES: | |
798 | err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid, | |
799 | uid, seq, data, nlmsg_len(nlh), | |
800 | loginuid, sessionid, sid); | |
801 | break; | |
802 | case AUDIT_TRIM: | |
803 | audit_trim_trees(); | |
804 | ||
805 | audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid, | |
806 | uid, loginuid, sessionid, sid); | |
807 | ||
808 | audit_log_format(ab, " op=trim res=1"); | |
809 | audit_log_end(ab); | |
810 | break; | |
811 | case AUDIT_MAKE_EQUIV: { | |
812 | void *bufp = data; | |
813 | u32 sizes[2]; | |
814 | size_t msglen = nlmsg_len(nlh); | |
815 | char *old, *new; | |
816 | ||
817 | err = -EINVAL; | |
818 | if (msglen < 2 * sizeof(u32)) | |
819 | break; | |
820 | memcpy(sizes, bufp, 2 * sizeof(u32)); | |
821 | bufp += 2 * sizeof(u32); | |
822 | msglen -= 2 * sizeof(u32); | |
823 | old = audit_unpack_string(&bufp, &msglen, sizes[0]); | |
824 | if (IS_ERR(old)) { | |
825 | err = PTR_ERR(old); | |
826 | break; | |
827 | } | |
828 | new = audit_unpack_string(&bufp, &msglen, sizes[1]); | |
829 | if (IS_ERR(new)) { | |
830 | err = PTR_ERR(new); | |
831 | kfree(old); | |
832 | break; | |
833 | } | |
834 | /* OK, here comes... */ | |
835 | err = audit_tag_tree(old, new); | |
836 | ||
837 | audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid, | |
838 | uid, loginuid, sessionid, sid); | |
839 | ||
840 | audit_log_format(ab, " op=make_equiv old="); | |
841 | audit_log_untrustedstring(ab, old); | |
842 | audit_log_format(ab, " new="); | |
843 | audit_log_untrustedstring(ab, new); | |
844 | audit_log_format(ab, " res=%d", !err); | |
845 | audit_log_end(ab); | |
846 | kfree(old); | |
847 | kfree(new); | |
848 | break; | |
849 | } | |
850 | case AUDIT_SIGNAL_INFO: | |
851 | len = 0; | |
852 | if (audit_sig_sid) { | |
853 | err = security_secid_to_secctx(audit_sig_sid, &ctx, &len); | |
854 | if (err) | |
855 | return err; | |
856 | } | |
857 | sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL); | |
858 | if (!sig_data) { | |
859 | if (audit_sig_sid) | |
860 | security_release_secctx(ctx, len); | |
861 | return -ENOMEM; | |
862 | } | |
863 | sig_data->uid = audit_sig_uid; | |
864 | sig_data->pid = audit_sig_pid; | |
865 | if (audit_sig_sid) { | |
866 | memcpy(sig_data->ctx, ctx, len); | |
867 | security_release_secctx(ctx, len); | |
868 | } | |
869 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO, | |
870 | 0, 0, sig_data, sizeof(*sig_data) + len); | |
871 | kfree(sig_data); | |
872 | break; | |
873 | case AUDIT_TTY_GET: { | |
874 | struct audit_tty_status s; | |
875 | struct task_struct *tsk; | |
876 | unsigned long flags; | |
877 | ||
878 | rcu_read_lock(); | |
879 | tsk = find_task_by_vpid(pid); | |
880 | if (tsk && lock_task_sighand(tsk, &flags)) { | |
881 | s.enabled = tsk->signal->audit_tty != 0; | |
882 | unlock_task_sighand(tsk, &flags); | |
883 | } else | |
884 | err = -ESRCH; | |
885 | rcu_read_unlock(); | |
886 | ||
887 | if (!err) | |
888 | audit_send_reply(NETLINK_CB(skb).pid, seq, | |
889 | AUDIT_TTY_GET, 0, 0, &s, sizeof(s)); | |
890 | break; | |
891 | } | |
892 | case AUDIT_TTY_SET: { | |
893 | struct audit_tty_status *s; | |
894 | struct task_struct *tsk; | |
895 | unsigned long flags; | |
896 | ||
897 | if (nlh->nlmsg_len < sizeof(struct audit_tty_status)) | |
898 | return -EINVAL; | |
899 | s = data; | |
900 | if (s->enabled != 0 && s->enabled != 1) | |
901 | return -EINVAL; | |
902 | rcu_read_lock(); | |
903 | tsk = find_task_by_vpid(pid); | |
904 | if (tsk && lock_task_sighand(tsk, &flags)) { | |
905 | tsk->signal->audit_tty = s->enabled != 0; | |
906 | unlock_task_sighand(tsk, &flags); | |
907 | } else | |
908 | err = -ESRCH; | |
909 | rcu_read_unlock(); | |
910 | break; | |
911 | } | |
912 | default: | |
913 | err = -EINVAL; | |
914 | break; | |
915 | } | |
916 | ||
917 | return err < 0 ? err : 0; | |
918 | } | |
919 | ||
920 | /* | |
921 | * Get message from skb. Each message is processed by audit_receive_msg. | |
922 | * Malformed skbs with wrong length are discarded silently. | |
923 | */ | |
924 | static void audit_receive_skb(struct sk_buff *skb) | |
925 | { | |
926 | struct nlmsghdr *nlh; | |
927 | /* | |
928 | * len MUST be signed for NLMSG_NEXT to be able to dec it below 0 | |
929 | * if the nlmsg_len was not aligned | |
930 | */ | |
931 | int len; | |
932 | int err; | |
933 | ||
934 | nlh = nlmsg_hdr(skb); | |
935 | len = skb->len; | |
936 | ||
937 | while (NLMSG_OK(nlh, len)) { | |
938 | err = audit_receive_msg(skb, nlh); | |
939 | /* if err or if this message says it wants a response */ | |
940 | if (err || (nlh->nlmsg_flags & NLM_F_ACK)) | |
941 | netlink_ack(skb, nlh, err); | |
942 | ||
943 | nlh = NLMSG_NEXT(nlh, len); | |
944 | } | |
945 | } | |
946 | ||
947 | /* Receive messages from netlink socket. */ | |
948 | static void audit_receive(struct sk_buff *skb) | |
949 | { | |
950 | mutex_lock(&audit_cmd_mutex); | |
951 | audit_receive_skb(skb); | |
952 | mutex_unlock(&audit_cmd_mutex); | |
953 | } | |
954 | ||
955 | /* Initialize audit support at boot time. */ | |
956 | static int __init audit_init(void) | |
957 | { | |
958 | int i; | |
959 | ||
960 | if (audit_initialized == AUDIT_DISABLED) | |
961 | return 0; | |
962 | ||
963 | printk(KERN_INFO "audit: initializing netlink socket (%s)\n", | |
964 | audit_default ? "enabled" : "disabled"); | |
965 | audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, 0, | |
966 | audit_receive, NULL, THIS_MODULE); | |
967 | if (!audit_sock) | |
968 | audit_panic("cannot initialize netlink socket"); | |
969 | else | |
970 | audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT; | |
971 | ||
972 | skb_queue_head_init(&audit_skb_queue); | |
973 | skb_queue_head_init(&audit_skb_hold_queue); | |
974 | audit_initialized = AUDIT_INITIALIZED; | |
975 | audit_enabled = audit_default; | |
976 | audit_ever_enabled |= !!audit_default; | |
977 | ||
978 | audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized"); | |
979 | ||
980 | for (i = 0; i < AUDIT_INODE_BUCKETS; i++) | |
981 | INIT_LIST_HEAD(&audit_inode_hash[i]); | |
982 | ||
983 | return 0; | |
984 | } | |
985 | __initcall(audit_init); | |
986 | ||
987 | /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */ | |
988 | static int __init audit_enable(char *str) | |
989 | { | |
990 | audit_default = !!simple_strtol(str, NULL, 0); | |
991 | if (!audit_default) | |
992 | audit_initialized = AUDIT_DISABLED; | |
993 | ||
994 | printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled"); | |
995 | ||
996 | if (audit_initialized == AUDIT_INITIALIZED) { | |
997 | audit_enabled = audit_default; | |
998 | audit_ever_enabled |= !!audit_default; | |
999 | } else if (audit_initialized == AUDIT_UNINITIALIZED) { | |
1000 | printk(" (after initialization)"); | |
1001 | } else { | |
1002 | printk(" (until reboot)"); | |
1003 | } | |
1004 | printk("\n"); | |
1005 | ||
1006 | return 1; | |
1007 | } | |
1008 | ||
1009 | __setup("audit=", audit_enable); | |
1010 | ||
1011 | static void audit_buffer_free(struct audit_buffer *ab) | |
1012 | { | |
1013 | unsigned long flags; | |
1014 | ||
1015 | if (!ab) | |
1016 | return; | |
1017 | ||
1018 | if (ab->skb) | |
1019 | kfree_skb(ab->skb); | |
1020 | ||
1021 | spin_lock_irqsave(&audit_freelist_lock, flags); | |
1022 | if (audit_freelist_count > AUDIT_MAXFREE) | |
1023 | kfree(ab); | |
1024 | else { | |
1025 | audit_freelist_count++; | |
1026 | list_add(&ab->list, &audit_freelist); | |
1027 | } | |
1028 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
1029 | } | |
1030 | ||
1031 | static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx, | |
1032 | gfp_t gfp_mask, int type) | |
1033 | { | |
1034 | unsigned long flags; | |
1035 | struct audit_buffer *ab = NULL; | |
1036 | struct nlmsghdr *nlh; | |
1037 | ||
1038 | spin_lock_irqsave(&audit_freelist_lock, flags); | |
1039 | if (!list_empty(&audit_freelist)) { | |
1040 | ab = list_entry(audit_freelist.next, | |
1041 | struct audit_buffer, list); | |
1042 | list_del(&ab->list); | |
1043 | --audit_freelist_count; | |
1044 | } | |
1045 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
1046 | ||
1047 | if (!ab) { | |
1048 | ab = kmalloc(sizeof(*ab), gfp_mask); | |
1049 | if (!ab) | |
1050 | goto err; | |
1051 | } | |
1052 | ||
1053 | ab->ctx = ctx; | |
1054 | ab->gfp_mask = gfp_mask; | |
1055 | ||
1056 | ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask); | |
1057 | if (!ab->skb) | |
1058 | goto nlmsg_failure; | |
1059 | ||
1060 | nlh = NLMSG_NEW(ab->skb, 0, 0, type, 0, 0); | |
1061 | ||
1062 | return ab; | |
1063 | ||
1064 | nlmsg_failure: /* Used by NLMSG_NEW */ | |
1065 | kfree_skb(ab->skb); | |
1066 | ab->skb = NULL; | |
1067 | err: | |
1068 | audit_buffer_free(ab); | |
1069 | return NULL; | |
1070 | } | |
1071 | ||
1072 | /** | |
1073 | * audit_serial - compute a serial number for the audit record | |
1074 | * | |
1075 | * Compute a serial number for the audit record. Audit records are | |
1076 | * written to user-space as soon as they are generated, so a complete | |
1077 | * audit record may be written in several pieces. The timestamp of the | |
1078 | * record and this serial number are used by the user-space tools to | |
1079 | * determine which pieces belong to the same audit record. The | |
1080 | * (timestamp,serial) tuple is unique for each syscall and is live from | |
1081 | * syscall entry to syscall exit. | |
1082 | * | |
1083 | * NOTE: Another possibility is to store the formatted records off the | |
1084 | * audit context (for those records that have a context), and emit them | |
1085 | * all at syscall exit. However, this could delay the reporting of | |
1086 | * significant errors until syscall exit (or never, if the system | |
1087 | * halts). | |
1088 | */ | |
1089 | unsigned int audit_serial(void) | |
1090 | { | |
1091 | static DEFINE_SPINLOCK(serial_lock); | |
1092 | static unsigned int serial = 0; | |
1093 | ||
1094 | unsigned long flags; | |
1095 | unsigned int ret; | |
1096 | ||
1097 | spin_lock_irqsave(&serial_lock, flags); | |
1098 | do { | |
1099 | ret = ++serial; | |
1100 | } while (unlikely(!ret)); | |
1101 | spin_unlock_irqrestore(&serial_lock, flags); | |
1102 | ||
1103 | return ret; | |
1104 | } | |
1105 | ||
1106 | static inline void audit_get_stamp(struct audit_context *ctx, | |
1107 | struct timespec *t, unsigned int *serial) | |
1108 | { | |
1109 | if (!ctx || !auditsc_get_stamp(ctx, t, serial)) { | |
1110 | *t = CURRENT_TIME; | |
1111 | *serial = audit_serial(); | |
1112 | } | |
1113 | } | |
1114 | ||
1115 | /* Obtain an audit buffer. This routine does locking to obtain the | |
1116 | * audit buffer, but then no locking is required for calls to | |
1117 | * audit_log_*format. If the tsk is a task that is currently in a | |
1118 | * syscall, then the syscall is marked as auditable and an audit record | |
1119 | * will be written at syscall exit. If there is no associated task, tsk | |
1120 | * should be NULL. */ | |
1121 | ||
1122 | /** | |
1123 | * audit_log_start - obtain an audit buffer | |
1124 | * @ctx: audit_context (may be NULL) | |
1125 | * @gfp_mask: type of allocation | |
1126 | * @type: audit message type | |
1127 | * | |
1128 | * Returns audit_buffer pointer on success or NULL on error. | |
1129 | * | |
1130 | * Obtain an audit buffer. This routine does locking to obtain the | |
1131 | * audit buffer, but then no locking is required for calls to | |
1132 | * audit_log_*format. If the task (ctx) is a task that is currently in a | |
1133 | * syscall, then the syscall is marked as auditable and an audit record | |
1134 | * will be written at syscall exit. If there is no associated task, then | |
1135 | * task context (ctx) should be NULL. | |
1136 | */ | |
1137 | struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, | |
1138 | int type) | |
1139 | { | |
1140 | struct audit_buffer *ab = NULL; | |
1141 | struct timespec t; | |
1142 | unsigned int uninitialized_var(serial); | |
1143 | int reserve; | |
1144 | unsigned long timeout_start = jiffies; | |
1145 | ||
1146 | if (audit_initialized != AUDIT_INITIALIZED) | |
1147 | return NULL; | |
1148 | ||
1149 | if (unlikely(audit_filter_type(type))) | |
1150 | return NULL; | |
1151 | ||
1152 | if (gfp_mask & __GFP_WAIT) | |
1153 | reserve = 0; | |
1154 | else | |
1155 | reserve = 5; /* Allow atomic callers to go up to five | |
1156 | entries over the normal backlog limit */ | |
1157 | ||
1158 | while (audit_backlog_limit | |
1159 | && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) { | |
1160 | if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time | |
1161 | && time_before(jiffies, timeout_start + audit_backlog_wait_time)) { | |
1162 | ||
1163 | /* Wait for auditd to drain the queue a little */ | |
1164 | DECLARE_WAITQUEUE(wait, current); | |
1165 | set_current_state(TASK_INTERRUPTIBLE); | |
1166 | add_wait_queue(&audit_backlog_wait, &wait); | |
1167 | ||
1168 | if (audit_backlog_limit && | |
1169 | skb_queue_len(&audit_skb_queue) > audit_backlog_limit) | |
1170 | schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies); | |
1171 | ||
1172 | __set_current_state(TASK_RUNNING); | |
1173 | remove_wait_queue(&audit_backlog_wait, &wait); | |
1174 | continue; | |
1175 | } | |
1176 | if (audit_rate_check() && printk_ratelimit()) | |
1177 | printk(KERN_WARNING | |
1178 | "audit: audit_backlog=%d > " | |
1179 | "audit_backlog_limit=%d\n", | |
1180 | skb_queue_len(&audit_skb_queue), | |
1181 | audit_backlog_limit); | |
1182 | audit_log_lost("backlog limit exceeded"); | |
1183 | audit_backlog_wait_time = audit_backlog_wait_overflow; | |
1184 | wake_up(&audit_backlog_wait); | |
1185 | return NULL; | |
1186 | } | |
1187 | ||
1188 | ab = audit_buffer_alloc(ctx, gfp_mask, type); | |
1189 | if (!ab) { | |
1190 | audit_log_lost("out of memory in audit_log_start"); | |
1191 | return NULL; | |
1192 | } | |
1193 | ||
1194 | audit_get_stamp(ab->ctx, &t, &serial); | |
1195 | ||
1196 | audit_log_format(ab, "audit(%lu.%03lu:%u): ", | |
1197 | t.tv_sec, t.tv_nsec/1000000, serial); | |
1198 | return ab; | |
1199 | } | |
1200 | ||
1201 | /** | |
1202 | * audit_expand - expand skb in the audit buffer | |
1203 | * @ab: audit_buffer | |
1204 | * @extra: space to add at tail of the skb | |
1205 | * | |
1206 | * Returns 0 (no space) on failed expansion, or available space if | |
1207 | * successful. | |
1208 | */ | |
1209 | static inline int audit_expand(struct audit_buffer *ab, int extra) | |
1210 | { | |
1211 | struct sk_buff *skb = ab->skb; | |
1212 | int oldtail = skb_tailroom(skb); | |
1213 | int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask); | |
1214 | int newtail = skb_tailroom(skb); | |
1215 | ||
1216 | if (ret < 0) { | |
1217 | audit_log_lost("out of memory in audit_expand"); | |
1218 | return 0; | |
1219 | } | |
1220 | ||
1221 | skb->truesize += newtail - oldtail; | |
1222 | return newtail; | |
1223 | } | |
1224 | ||
1225 | /* | |
1226 | * Format an audit message into the audit buffer. If there isn't enough | |
1227 | * room in the audit buffer, more room will be allocated and vsnprint | |
1228 | * will be called a second time. Currently, we assume that a printk | |
1229 | * can't format message larger than 1024 bytes, so we don't either. | |
1230 | */ | |
1231 | static void audit_log_vformat(struct audit_buffer *ab, const char *fmt, | |
1232 | va_list args) | |
1233 | { | |
1234 | int len, avail; | |
1235 | struct sk_buff *skb; | |
1236 | va_list args2; | |
1237 | ||
1238 | if (!ab) | |
1239 | return; | |
1240 | ||
1241 | BUG_ON(!ab->skb); | |
1242 | skb = ab->skb; | |
1243 | avail = skb_tailroom(skb); | |
1244 | if (avail == 0) { | |
1245 | avail = audit_expand(ab, AUDIT_BUFSIZ); | |
1246 | if (!avail) | |
1247 | goto out; | |
1248 | } | |
1249 | va_copy(args2, args); | |
1250 | len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args); | |
1251 | if (len >= avail) { | |
1252 | /* The printk buffer is 1024 bytes long, so if we get | |
1253 | * here and AUDIT_BUFSIZ is at least 1024, then we can | |
1254 | * log everything that printk could have logged. */ | |
1255 | avail = audit_expand(ab, | |
1256 | max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail)); | |
1257 | if (!avail) | |
1258 | goto out; | |
1259 | len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2); | |
1260 | } | |
1261 | va_end(args2); | |
1262 | if (len > 0) | |
1263 | skb_put(skb, len); | |
1264 | out: | |
1265 | return; | |
1266 | } | |
1267 | ||
1268 | /** | |
1269 | * audit_log_format - format a message into the audit buffer. | |
1270 | * @ab: audit_buffer | |
1271 | * @fmt: format string | |
1272 | * @...: optional parameters matching @fmt string | |
1273 | * | |
1274 | * All the work is done in audit_log_vformat. | |
1275 | */ | |
1276 | void audit_log_format(struct audit_buffer *ab, const char *fmt, ...) | |
1277 | { | |
1278 | va_list args; | |
1279 | ||
1280 | if (!ab) | |
1281 | return; | |
1282 | va_start(args, fmt); | |
1283 | audit_log_vformat(ab, fmt, args); | |
1284 | va_end(args); | |
1285 | } | |
1286 | ||
1287 | /** | |
1288 | * audit_log_hex - convert a buffer to hex and append it to the audit skb | |
1289 | * @ab: the audit_buffer | |
1290 | * @buf: buffer to convert to hex | |
1291 | * @len: length of @buf to be converted | |
1292 | * | |
1293 | * No return value; failure to expand is silently ignored. | |
1294 | * | |
1295 | * This function will take the passed buf and convert it into a string of | |
1296 | * ascii hex digits. The new string is placed onto the skb. | |
1297 | */ | |
1298 | void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf, | |
1299 | size_t len) | |
1300 | { | |
1301 | int i, avail, new_len; | |
1302 | unsigned char *ptr; | |
1303 | struct sk_buff *skb; | |
1304 | static const unsigned char *hex = "0123456789ABCDEF"; | |
1305 | ||
1306 | if (!ab) | |
1307 | return; | |
1308 | ||
1309 | BUG_ON(!ab->skb); | |
1310 | skb = ab->skb; | |
1311 | avail = skb_tailroom(skb); | |
1312 | new_len = len<<1; | |
1313 | if (new_len >= avail) { | |
1314 | /* Round the buffer request up to the next multiple */ | |
1315 | new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1); | |
1316 | avail = audit_expand(ab, new_len); | |
1317 | if (!avail) | |
1318 | return; | |
1319 | } | |
1320 | ||
1321 | ptr = skb_tail_pointer(skb); | |
1322 | for (i=0; i<len; i++) { | |
1323 | *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */ | |
1324 | *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */ | |
1325 | } | |
1326 | *ptr = 0; | |
1327 | skb_put(skb, len << 1); /* new string is twice the old string */ | |
1328 | } | |
1329 | ||
1330 | /* | |
1331 | * Format a string of no more than slen characters into the audit buffer, | |
1332 | * enclosed in quote marks. | |
1333 | */ | |
1334 | void audit_log_n_string(struct audit_buffer *ab, const char *string, | |
1335 | size_t slen) | |
1336 | { | |
1337 | int avail, new_len; | |
1338 | unsigned char *ptr; | |
1339 | struct sk_buff *skb; | |
1340 | ||
1341 | if (!ab) | |
1342 | return; | |
1343 | ||
1344 | BUG_ON(!ab->skb); | |
1345 | skb = ab->skb; | |
1346 | avail = skb_tailroom(skb); | |
1347 | new_len = slen + 3; /* enclosing quotes + null terminator */ | |
1348 | if (new_len > avail) { | |
1349 | avail = audit_expand(ab, new_len); | |
1350 | if (!avail) | |
1351 | return; | |
1352 | } | |
1353 | ptr = skb_tail_pointer(skb); | |
1354 | *ptr++ = '"'; | |
1355 | memcpy(ptr, string, slen); | |
1356 | ptr += slen; | |
1357 | *ptr++ = '"'; | |
1358 | *ptr = 0; | |
1359 | skb_put(skb, slen + 2); /* don't include null terminator */ | |
1360 | } | |
1361 | ||
1362 | /** | |
1363 | * audit_string_contains_control - does a string need to be logged in hex | |
1364 | * @string: string to be checked | |
1365 | * @len: max length of the string to check | |
1366 | */ | |
1367 | int audit_string_contains_control(const char *string, size_t len) | |
1368 | { | |
1369 | const unsigned char *p; | |
1370 | for (p = string; p < (const unsigned char *)string + len; p++) { | |
1371 | if (*p == '"' || *p < 0x21 || *p > 0x7e) | |
1372 | return 1; | |
1373 | } | |
1374 | return 0; | |
1375 | } | |
1376 | ||
1377 | /** | |
1378 | * audit_log_n_untrustedstring - log a string that may contain random characters | |
1379 | * @ab: audit_buffer | |
1380 | * @len: length of string (not including trailing null) | |
1381 | * @string: string to be logged | |
1382 | * | |
1383 | * This code will escape a string that is passed to it if the string | |
1384 | * contains a control character, unprintable character, double quote mark, | |
1385 | * or a space. Unescaped strings will start and end with a double quote mark. | |
1386 | * Strings that are escaped are printed in hex (2 digits per char). | |
1387 | * | |
1388 | * The caller specifies the number of characters in the string to log, which may | |
1389 | * or may not be the entire string. | |
1390 | */ | |
1391 | void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string, | |
1392 | size_t len) | |
1393 | { | |
1394 | if (audit_string_contains_control(string, len)) | |
1395 | audit_log_n_hex(ab, string, len); | |
1396 | else | |
1397 | audit_log_n_string(ab, string, len); | |
1398 | } | |
1399 | ||
1400 | /** | |
1401 | * audit_log_untrustedstring - log a string that may contain random characters | |
1402 | * @ab: audit_buffer | |
1403 | * @string: string to be logged | |
1404 | * | |
1405 | * Same as audit_log_n_untrustedstring(), except that strlen is used to | |
1406 | * determine string length. | |
1407 | */ | |
1408 | void audit_log_untrustedstring(struct audit_buffer *ab, const char *string) | |
1409 | { | |
1410 | audit_log_n_untrustedstring(ab, string, strlen(string)); | |
1411 | } | |
1412 | ||
1413 | /* This is a helper-function to print the escaped d_path */ | |
1414 | void audit_log_d_path(struct audit_buffer *ab, const char *prefix, | |
1415 | struct path *path) | |
1416 | { | |
1417 | char *p, *pathname; | |
1418 | ||
1419 | if (prefix) | |
1420 | audit_log_format(ab, " %s", prefix); | |
1421 | ||
1422 | /* We will allow 11 spaces for ' (deleted)' to be appended */ | |
1423 | pathname = kmalloc(PATH_MAX+11, ab->gfp_mask); | |
1424 | if (!pathname) { | |
1425 | audit_log_string(ab, "<no_memory>"); | |
1426 | return; | |
1427 | } | |
1428 | p = d_path(path, pathname, PATH_MAX+11); | |
1429 | if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */ | |
1430 | /* FIXME: can we save some information here? */ | |
1431 | audit_log_string(ab, "<too_long>"); | |
1432 | } else | |
1433 | audit_log_untrustedstring(ab, p); | |
1434 | kfree(pathname); | |
1435 | } | |
1436 | ||
1437 | void audit_log_key(struct audit_buffer *ab, char *key) | |
1438 | { | |
1439 | audit_log_format(ab, " key="); | |
1440 | if (key) | |
1441 | audit_log_untrustedstring(ab, key); | |
1442 | else | |
1443 | audit_log_format(ab, "(null)"); | |
1444 | } | |
1445 | ||
1446 | /** | |
1447 | * audit_log_end - end one audit record | |
1448 | * @ab: the audit_buffer | |
1449 | * | |
1450 | * The netlink_* functions cannot be called inside an irq context, so | |
1451 | * the audit buffer is placed on a queue and a tasklet is scheduled to | |
1452 | * remove them from the queue outside the irq context. May be called in | |
1453 | * any context. | |
1454 | */ | |
1455 | void audit_log_end(struct audit_buffer *ab) | |
1456 | { | |
1457 | if (!ab) | |
1458 | return; | |
1459 | if (!audit_rate_check()) { | |
1460 | audit_log_lost("rate limit exceeded"); | |
1461 | } else { | |
1462 | struct nlmsghdr *nlh = nlmsg_hdr(ab->skb); | |
1463 | nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0); | |
1464 | ||
1465 | if (audit_pid) { | |
1466 | skb_queue_tail(&audit_skb_queue, ab->skb); | |
1467 | wake_up_interruptible(&kauditd_wait); | |
1468 | } else { | |
1469 | audit_printk_skb(ab->skb); | |
1470 | } | |
1471 | ab->skb = NULL; | |
1472 | } | |
1473 | audit_buffer_free(ab); | |
1474 | } | |
1475 | ||
1476 | /** | |
1477 | * audit_log - Log an audit record | |
1478 | * @ctx: audit context | |
1479 | * @gfp_mask: type of allocation | |
1480 | * @type: audit message type | |
1481 | * @fmt: format string to use | |
1482 | * @...: variable parameters matching the format string | |
1483 | * | |
1484 | * This is a convenience function that calls audit_log_start, | |
1485 | * audit_log_vformat, and audit_log_end. It may be called | |
1486 | * in any context. | |
1487 | */ | |
1488 | void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type, | |
1489 | const char *fmt, ...) | |
1490 | { | |
1491 | struct audit_buffer *ab; | |
1492 | va_list args; | |
1493 | ||
1494 | ab = audit_log_start(ctx, gfp_mask, type); | |
1495 | if (ab) { | |
1496 | va_start(args, fmt); | |
1497 | audit_log_vformat(ab, fmt, args); | |
1498 | va_end(args); | |
1499 | audit_log_end(ab); | |
1500 | } | |
1501 | } | |
1502 | ||
1503 | EXPORT_SYMBOL(audit_log_start); | |
1504 | EXPORT_SYMBOL(audit_log_end); | |
1505 | EXPORT_SYMBOL(audit_log_format); | |
1506 | EXPORT_SYMBOL(audit_log); |